Mercury Orbit Insertion March 18, 2011 UTC (March 17, 2011 EDT) A NASA Discovery Mission Media Contacts NASA Headquarters Policy/Program Management Dwayne C. Brown (202) 358-1726 [email protected] The Johns Hopkins University Applied Physics Laboratory Mission Management, Spacecraft Operations Paulette W. Campbell (240) 228-6792 or (443) 778-6792 [email protected] Carnegie Institution of Washington Principal Investigator Institution Tina McDowell (202) 939-1120 [email protected] Mission Overview Key Spacecraft Characteristics MESSENGER is a scientific investigation . Redundant major systems provide critical backup. of the planet Mercury. Understanding . Passive thermal design utilizing ceramic-cloth Mercury, and the forces that have shaped sunshade requires no high-temperature electronics. it, is fundamental to understanding the . Fixed phased-array antennas replace a deployable terrestrial planets and their evolution. high-gain antenna. The MESSENGER (MErcury Surface, Space . Custom solar arrays produce power at safe operating ENvironment, GEochemistry, and Ranging) temperatures near Mercury. spacecraft will orbit Mercury following three flybys of that planet. The orbital phase will MESSENGER is designed to answer six use the flyby data as an initial guide to broad scientific questions: perform a focused scientific investigation of . Why is Mercury so dense? this enigmatic world. What is the geologic history of Mercury? MESSENGER will investigate key . What is the nature of Mercury’s magnetic field? scientific questions regarding Mercury’s . What is the structure of Mercury’s core? characteristics and environment during . What are the unusual materials at Mercury’s poles? these two complementary mission phases. What volatiles are important at Mercury? Data are provided by an optimized set of miniaturized space instruments and the MESSENGER provides: spacecraft tele commun ications system. Multiple flybys for global mapping, detailed study of high-priority MESSENGER will enter orbit about Mercury targets, and probing of the atmosphere and magnetosphere. in March 2011 and carry out comprehensive . An orbiter for detailed characterization of the surface, measurements for one Earth year. Orbital interior, atmosphere, and magnetosphere. data collection concludes in March 2012. An education and public outreach program to produce exhibits, plain-language books, educational modules, and teacher training through partnerships. Mission Summary Launch: 3 August 2004 Mercury flybys (3): 14 January 2008, Launch vehicle: Delta II 7925H-9.5 6 October 2008, Earth flyby: 2 August 2005 29 September 2009 Venus flybys (2): 24 October 2006, Mercury orbit insertion: 17 March 2011 (EDT) 5 June 2007 18 March 2001 (UTC) MESSENGER — Mercury, the Last Frontier of the Terrestrial Planets Understanding Mercury is fundamental to understanding terrestrial planet evolution. Discoveries from MESSENGER’s Mercury Flybys: In addition to providing key gravity assists that enable orbit insertion as well as opportunities to test scientific operations and command sequences for all payload instruments, MESSENGER’s three flybys of Mercury yielded a number of discoveries that have markedly changed our view of Mercury and influenced our preparations for orbital operations. These include: Geology • Volcanism was widespread on Mercury and extended from Antenna Sunshade before the end of heavy bombardment to the second half of solar system history. • Mercury experienced explosive volcanism, indicating that interior volatile contents were at least locally much higher than thought. • Contraction spanned much of Mercury’s geologic history. EPPS Composition and surface-derived exosphere • Mercury’s surface silicates, even in fresh crater ejecta, GRNS MLA contain little or no ferrous oxide. XRS MDIS • Mercury’s thermal neutron flux matches that of several MASCS lunar maria, indicating that iron and titanium are present in MAG comparable collective abundances, perhaps as oxides. Science Payload • Magnesium and ionized calcium are present in Mercury’s exosphere. Mercury Dual Imaging System Energetic Particle and (MDIS) takes detailed color and Plasma Spectrometer (EPPS) Internal structure and dynamics monochrome images of Mercury’s measures charged particles in • The equatorial topographic relief of Mercury, in agreement surface. Mercury’s magnetosphere. with earlier radar results, is at least 5.5 km. Gamma-Ray and Neutron Mercury Laser Altimeter (MLA) Spectrometer (GRNS) measures measures topography of surface • The case for a liquid outer core in Mercury is surface elements (including polar features; determines whether greatly strengthened. materials). Mercury has a fluid core. • Mercury’s internal magnetic field is dominantly dipolar X-Ray Spectrometer (XRS) maps Radio Science uses Doppler with a vector moment closely aligned with the spin axis. elements in Mercury’s crust. tracking to determine Mercury’s mass distribution. Magnetometer (MAG) maps Magnetospheric dynamics Mercury’s magnetic field. • Mercury’s magnetosphere is more responsive to Mercury Atmospheric interplanetary magnetic field (IMF) fluctuations than those and Surface Composition of other planets. Spectrometer (MASCS) • Under southward IMF, rates of magnetic reconnection measures atmospheric are ~10 times that typical at Earth. species and surface minerals. • Loading of magnetic flux in Mercury’s magnetic tail can be so intense that much of Mercury’s dayside could be exposed to the shocked solar wind of the magnetosheath during such episodes. Mission Management Principal Investigator: Sean C. Solomon, Instruments: JHU/APL, Carnegie Institution of Washington NASA Goddard Space Flight Center, Project Management: The Johns Hopkins University University of Colorado, Applied Physics Laboratory (JHU/APL) University of Michigan Spacecraft Integration Structure: Composite Optics, Inc. and Operation: JHU/APL Propulsion: GenCorp Aerojet Navigation: KinetX, Inc. On the Web MESSENGER mission: http://messenger.jhuapl.edu NASA Discovery Program: http://discovery.nasa.gov FS2 03-11 NASA’s Mission to Mercury Table of Contents Media Services Information ............................................................................................................. 7 MESSENGER Quick Facts .................................................................................................................. 8 Mercury Orbit Insertion & Station Keeping .................................................................................... 9 Getting into Mercury orbit…. ............................................................................................................. 9 ….and staying there ......................................................................................................................... 12 Science orbit: Working at Mercury .................................................................................................... 12 Observing the surface ....................................................................................................................... 13 Orchestrating the observations ......................................................................................................... 14 Mercury at a Glance ........................................................................................................................ 17 Why Mercury? ................................................................................................................................. 18 Question 1: Why is Mercury so dense? ............................................................................................. 18 Question 2: What is the geologic history of Mercury? ....................................................................... 19 Question 3: What is the nature of Mercury’s magnetic field?............................................................. 20 Question 4: What is the structure of Mercury’s core? ........................................................................ 21 Question 5: What are the unusual materials at Mercury’s poles? ....................................................... 21 Question 6: What volatiles are important at Mercury?....................................................................... 23 Highlights from the Mercury Flybys .............................................................................................. 24 The Spacecraft ................................................................................................................................. 41 Science payload ................................................................................................................................ 42 Spacecraft systems and components ................................................................................................. 46 Hardware suppliers ........................................................................................................................... 49 Mission Summary ............................................................................................................................ 50 Cruise trajectory ............................................................................................................................... 50 Launch ............................................................................................................................................. 52 Earth flyby highlights .......................................................................................................................